1. Field of the Invention
The present invention relates to organogermanium compounds having new structures and a strong opioid peptide-degrading enzyme inhibitor containing the same as a principal ingredient.
2. Description of the Prior Art
Germanium (Ge), known as a homologue of carbon, has semiconductive effect like silicon (Si) as a special property and, in addition, it has been studied in this aspect for a long time. Recently, the studies of organogermanium compounds have been advanced and the results thereof have been reported and they have attracted public attention in various technical fields.
It is well known from reports of numerous scientific meetings and literature that a carboxyethylgermanium sesquioxide (GeCH.sub.2 CH.sub.2 COOH).sub.2 O.sub.3, as a macromolecular compound (a propionic acid derivative of germanium) containing a 12-membered ring as a unit structure in which germanium atoms and oxygen atoms are arranged alternately, has quite excellent physiological effects such as strong hypotensive and antineoplastic effects, and it is free from toxicity or adverse reaction.
It has also been reported that when the above mentioned organogermanium compound is administered to a patient who complains of pain such as a cancerous pain, the growth of the tumor is inhibited and the dose of a narcotic analgesic such as morphine required for relieving the pain can be reduced. For this fact, the following hypothesis has been given.
Namely, when morphine or the like is administered, peptides generally called "opioid peptides" are liberated in vivo. This opioid peptide and morphine share the same receptor to control the autoanalgesic activity in vivo. A reason why the dose of morphine or the like can be reduced by the administration of the organogermanium compound is that the organogermanium compound inhibits the action of opioid peptide-degrading enzyme which inactivate the opioid peptide by decomposition in vivo to improve the efficiency of the opioid peptide in vivo.
However, the mechanism of the physiological activity of the organogermanium compound has not fully been known. As for the antineoplastic effects, some researchers reported that the effect is realized based on a germanium-oxygen bond in the structure. If an organogermanium compound containing an analogous atom in place of the oxygen atom can be synthesized, the use of the resulting compound for a purpose different from that of the known organogermanium compound can be expected.